The mechanical design of hydraulic turbines is conditioned by the dynamic response of the runner that is usually estimated by a computational model. Nevertheless, the runner has complex boundary conditions that are difficult to include in the computational model. One of these boundary conditions is the water in which the runner is submerged. The effect of the added mass and damping of water can...

We investigate the damping of neutron star r-modes due to the presence of a viscous boundary (Ekman) layer at the interface between the crust and the core. Our study is motivated by the possibility that the gravitational-wave driven instability of the inertial r-modes may become active in rapidly spinning neutron stars, eg. in low-mass X-ray binaries, and the fact that a viscous Ekman layer at ...

A procedure is presented for modal and damping synthesis of flexible space structures from subsystem tests and/or analyses. In view of the various damping mechanism operative in a space structure, their contribution to total system damping and its compatibility with dynamic testing procedures, the spacecraft subsystems are identified as joints and components. The dynamics of joint subsystems is...

We study the global existence, uniqueness, and asymptotic behavior of solutions for a class of generalized plate-membrane-like systems with nonlinear damping and source acting both interior and on boundary.

At the initial phase of the mechanical product development, it is very important to effectively obtain the modal damping ratio of the bolted joint structure for accurately predicting dynamic response. The energy dissipation has been estimated using a finite element model incorporating the effect of pretension force of the bolted joint. First, the modal damping ratios of the first four modes are...

We present some models of viscoelastic systems with long-memory behaviour; we then provide both thorough mathematical analysis and numerical simulations of these models by means of so-called diiusive representations. The models under consideration are the basic harmonic oscillator with fractional damping, the generalized Lokshin model of waves, and also the boundary feedback control of the Eule...

therefore the damping layer has to be large enough to prevent reentrant waves at the physical boundary. Hence In this paper we develop a method for the simulation of wave propagation on artificially bounded domains. The acoustic wave the approach is not only costly in terms of memory requireequation is solved at all points away from the boundaries by a ments but also it is not very flexible. In...

In this paper, an active vibration control of a translating tensioned steel strip in the zinc galvanizing line is investigated. The dynamics of the moving strip is modeled as an Euler-Bernoulli beam with nonlinear tension. The control objective is to suppress the transverse vibrations of the strip via boundary control. A right boundary control law based upon the Lyapunov’s second method is deri...

An immersed boundary technique is used to model a riblet covered surface on one wall of a channel bounding fully developed turbulent flow. The conjecture that the beneficial drag reduction effect of riblets is a result of the damping of cross-flow velocity fluctuations is then examined. This possibility has been discussed by others but is unverified. The damping effect is explicitly modelled by...

Baroclinic eddy equilibration and the roles of different boundary layer processes in limiting the baroclinic adjustment are studied using an atmosphere–ocean thermally coupled model. Boundary layer processes not only affect the dynamical constraint of the midlatitude baroclinic eddy equilibration but also are important components in the underlying surface energy budget. The authors’ study shows...